Telephone-exchange system.



B. G; DUNHVAIVI.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED Nov. 2o, |916.

2 SHEETS-SHEET1.

Patented Jhne 25, 1918.

G. DUNHAM. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED NOV. 20. i916.

2 SHEETS-SHEET 2.

- I Patented June 25, 1918.

* s o i roti,

BERT G. IDUNHAM, OF HAWTHORNE, NEW JERSEY, ASSIGNOR TO WESTERN ELCTR COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed November 20, 1916.

To all whom it may concern.'

Be it known that I, BERT G. DUNHAM, a citizen of the United States, residing at Hawthorne, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone ex' change. systems wherein automatic finder switches are apportioned to calling lines by an extended starter wire, and is an improvement upon the system disclosed in my Patent No. 1,205,523, granted November 21, 1916.

In systems of this character a relay is provided at each finder for disabling its release circuit, the relays of busy finders being included in the starter wire when the starter wire is extended through such busy finders. When such starter wire is grounded by the initiation of a call, to start the finder to which the starter wire is extended, the relays of such busy finders through which the starter wire extends are energized to prevent release of such finders, since the release of an intermediate finder would disrupt the starting circuit.

It was found in practice'that, with the circuit arrangement of saidpatent, if all the inders were busy and another call was initiated, the finders could not be released as long as the calling party had his receiver off the switchhoolr, since the disabling relays were held energized as long as the calling line circuit was closed.

By virtue of the present invention, this cannot occur, and the improvement consists in providing an electromagnetic responsive device for the group of finders which is operated over a circuit closed when all the finders are busy, and which, when operated, prevents the operation of said disabling relays.

The invention will be more readily understood when described with reference to the accompanying drawings, wherein Figures 1 and 2 illustrate one embodiment of the Specification of Letters Patent.

Patented J une 25, 1018..

Serial No. 132,373.

its outer armature, energizes relays a, b, common to the group of lines containing substation E. Relay a, in attracting its right armature, grounds multiple segment 104 of the group to which substation E belongs to render the group calling. Relay b, in attracting its right armature, closes the following circuit to energize the escape magnet 106 of the line finder side switch:

. conductor m grounded at the armature and back contact of the calling supervisory relay in the same manner as is disclosed in the before-mentioned Patent No. 1,205,523 of the automatic or manual switch to which conductors 121,122,125 and m are connected, right armature and front contact of relay b, conductor 108, armatures and back contacts of magnets 107, 105, arm 1 of the inder side switch and its first contact, escape magnet 106 of the finder, and magnet 105 to free poleI of battery. Magnet 105 is marginal and is not energized in this circuit. The escape magnet 106 is constructed to release the side switch from position to position, upon its energization.

In position 2, arm 1 of the finder side switch connects magnet 105 over the back contacts of magnets 105, 107, to grounded conductor 108, whereupon the finder brush shaft 119 is given a primary movement by the operation of such magnet 105. In position 2, arm 2 closes the following circuit for relay 116: free pole of battery, magnet 107, arm 2, left winding of relay 116, armature and back contact of magnet 107 to grounded conductor 108. This relay attracts its armature upon the closure of this circuit, but magnet 107 is marginal and remains inert. Relay 116, at its inner armature and front contact, connects the escape magnet over arm 3 and its second contact to the group brush 115. When brush 115 encounters the calling group segment 104, now grounded, escape magnet 106 energizes over the following circuit, and releases the side switch into position 3: free pole of battery, magnets 105,106, conductors 117,118, inner armature and front contact of relay 116, arm 3 and its second contact, conductors 120, 130, brush 115, segment 104C, now grounded at the armature and front contact of relay a. Arm 1, in moving out of position 2, opens the circuit of magnet 105, thus stopping theprimary movement of the lnder brush shaft 119 with a set of brushes 110, 111, 112 in operative relation to mul- `tiples of the calling line group containing those of the calling line 101, 113 and 114.

In position 3, relay 116 is energized over the following circuit: free pole of battery, magnets 105, 106, arm 2 and its third contact, left winding of relay 116, armature and back contact of magnet 107, grounded conductor 108. Magnet 106 is `also marginal and neither this magnet nor magnet 105 becomes energized in thiscircuit. Relay 11'6, at its outerL armature and front contact, closes` the following circuit to operate vthe secondary stepping magnet 107 to drive the brushes 110, 111 and 112 over the multiples containing those of the calling line 101, 113 and 114: free pole of` battery, magnet 10,7,v outer yarmature and front Contact of relay 116, arm 1 and its third contact, armature and back contacts of 'magnets 105, 107, tofgrounded conductor 108. The magnet 107 interrupts the circuit traced through the left winding of relay 116, as well as its own f circuit, and this relay therefore vibrates list 'except when the brush 112 engages the ytest multiples 114 kof busy lines, when it is held energized from battery on such terminals, brush 112, conductor 120, arm 3 and its third contact, right winding of relay `116, to ground, as will be more particularly described hereinafter, When, however, :the brush 112 lreaches the calling line'multiple 114, relay 116 becomes vdenergized, andin retracting its outer armature, interrupts the stepping circuit of magnet 107, thus arresting the brushes,110,111,1 12 on the calling l-inefterminals 101, 113, 114. vSince ground is present on l'multiple 101 of the calling line, the following )circuit vis closed to energize escape magnet 106 z vfree 'pleof battery, magnets 105, y106, conductors 117 and 118, inner 'armature and back `Vcontact of relay 116, arm 5 and its third contact, 'brush 110, terminal 101ftogroun'd lat the inner armature and front contact of relay e. Magnet 106, upon its fener'gization,- releases 'the side switch intoposition4. In position 4, lthe calling line is vextended by, arms k4 and 5 to the conductors 121 122', whereupon the callingsupervisory'relay referred to is energiZed voverthe calling line 1circuit, and removes ground fromconductor m.

In position '4, arm '3 `of the wfinder side switch closes the 'following Vcircuit eto energize the'cutoff relay Z of the'c'allin'g line: free pole of battery, "resistance, '190, conductor 125,- arm 3,:and :its 'fourth contact, conductor120, brush 112,I terminal 15121, cutoff relay d, to ground. This kpotential applied to multiples l114'by brush 112,."holds relay l 116 f of 'afmoving'nder 'energized A over its right fwinding as jthefbrus'h l)112 'of fsuch finder wipes over such multiplies, as lliereinbefore described. `-Relay d, in attracting its armatures denergizes the linerelay e, which in retracting its inner armature, removes the calling condition from the multiples 101 of the calling line, and in vretracting its outer armature, denergizes group relays a, b. Relay a, in retracting its right armature, removes the calling condition from the multiples 104 of the calling group.

The switch connected to conductors 121, 122 to which the lfinder has extended the calling line E, may be either a manual or an automatic switch dependent upon the type of system.

Upon the termination of the conversation and the replacement of the receiver by the calling party, the supervisory relay connected to conductors 121, 122 becomes deenergized and closes the following circuit for the release magnet 127 of the finder: grounded conductor m, right armature and back contact of relay L, primary off-normal contact 126, release magnet 127, free pole of battery. Magnet 127, in attracting its left armature, locks itself over the 0normal Contact 126 to ground. When the linder brush shaft 119 is completely restored, this off-normal contact opens and unlocks the release magnet. The magnet 127 also restores the side switch which opens the circuit of the cut-off relay d.

Going back to that point in the operation where the removal of the receiver starts a finder seeking the calling line, it will be remembered that the initiation of such call energized group relay b, which, in attracting its right armature, extended the conductor m grounded at the armature and back contact of the calling supervisory relay, to the escape magnet 106 't0 initiate the primary movement of the finder brush shaft. In yparallel with magnet 106, a quick acting relay c is energized when relay b operates, this circuit being as follows: free pole of battery, relay c, spring z', conductors 133, 117, arm 1 and its first contact, arma tures and back contacts of magnets 105, 107, conductor 108, right armature and front contact of relay b togrounded conductor/m. Relayyc, by attracting its right armature, locks itself directly to grounded conductor 108, independently of side-switch arm 1, and by attracting its left armature, opens the connection between the grounded lefthand armature of relay a and the outstarter wire g, leading to the escape magnet 106,0f the next finder. If the finder shown in Fig. V1 had lbeen busy, the'calling supervisory relay would have been energized, andcon'sequently the circuit for relay c just traced would not have `been completed, and this relay failing to energize, the grounded left-hand armature of relay a would be connectedover the left armature of relay c to the out-starter wire g leadingto the escape magnet 106 of the next1 finder, to set the finder shaft lin motion seeking the calling line. Thus, the starter wire is normally extended to the neXt idle finder. Assuming the finder shown in F ig. 1 to be the next idle finder, the circuit may be continued as follows; in-starter wire f, left armature and back contact of relay a, relay b, conductor l1., right armature and back contact of magnet 127, resistance 137, free pole of battery. Relay Z2, in attracting its left armature, con-A nects the in and out-starter wires and g together, and in attracting its right armature, energizes the escape magnet 106 of such finder` as described, which, upon energizing, releases the side switch into position 2 to initiate the primary movement of the finder brush shaft. From this point on, the operations are the same as those already traced. The foregoing is shown and described in my patent referred to, and the improvement thereon, which is the subject matter of the present invention, will now be described.

It was found in practice that, with the circuit arrangement of said application, when all the finders were busy, an incoming waiting call would prevent the release of such finders, which release would ordinarily automatically take place upon the disconnecting act of the parties to the connections. This will be explained more particularly by reference to Fig. 2, wherein four sets of group relays a, 71,10, a', Z9', c', etc., and one line and one cut-off relay e, d, respectively, of a line in each group are shown. Assume that the four linders allotted to the four groups A, B, C, D, are busy and that one of the lines in group A initiates a call.

In the circuit arrangement of the patent referred to, the outer armature of relay e was permanently grounded. If all the finders were busy, the energization of relay e by the initiation of a call closed the circuit of relays a, Z) of group A in series, by way of conductor la (Figs. 1 and 2). Relay Z) in operating interposes a break in the circuit of the release magnet 127 to which conductor lc is connected to prevent the energization of such release magnet, and consequent denergization of relays a and Z2. ReL lays (I, and Z2 in operating closed the following circuit to energize relay b3 of the finder of group D, the next finder in so far as the starter wire is concerned: ground, left armatures and front contacts of relays a and b, left armature and back contact of relay c, not energized due to the absence of ground on conductor m, out starter wire g, left armature and back Contact of relay a3 of the group D, relay b3, conductor h3 to battery, over the right armature and back contact of release magnet 127 of the finder group D. Relay b3 in attracting its right armature interposes a break in the circuit of release magnet of the finder of roup D, to which conductor k3 is connecte and in attracting its left armature closes the following circuit for relay b2 of group C; grounded conductor f3, left armature and front contact of relay b3, left armature and back contact of relay c3, conductors g3, f2, left armature and back Contact of relay a2, relay b2, conductor k2, to free pole of battery over the right armature and back contact of the release magnet 127 of the finder of group C. Relay Z22 in attracting its right armature interposes a break in the circuit of release magnet of the finder of group C, and, in attracting its left armature, closes the following circuit for relay b1 of group B: -grounded conductor f2, left armature and front contact of relay Z22, leftarmature and back contact of relay c2, conductors g2, f1, left armature and back contact of relay al, relay b1, conductor h1, to free pole of battery over the left armature and back contact of release magnet 127 of the finder of group B. Relay b1 interposes a break in the circuit of such release magnet. It will thus be seen that the relays Z), b1, o2 and E23, etc., are all energized under the control of the line relay of the calling subscriber, and that inasmuch as these relays in attracting their right armatures interpose a break in the release circuits of the respective finders, none of these finders can release. To prevent this from occurring a slow relay 180 is provided.

. llien the finders of groups A, B, C, D, etc., are busy, the side switches of such finders are in their fourth position, and a circuit is closed for such slow relay 180, over arms Z, Z1, Z2, Z3 in series to ground., This relay in attracting its armature removes ground from the outer armatures of the line relays e, e1, e2, e", etc., thus preventing the energization of any of such relays from operating the group relays a, b, and tying up all the nders as described. When, however, one of the finders is restored, the circuit of relay 180 is interrupted at the 110 corresponding side-switch arm Z, Z1, Z2, Z3,- etc., whereupon relay 180 retracts its armature, reconnecting ground to the outer armatures of the line relays e, e1, e2, e3, etc.,

whereupon the energization of any of such i relays will operate the corresponding group relays and start such idler finder in motion seeking a calling line.

Relay 180 is made slow to retract its armature so that by the time the armature reaches its back contact the released finder and its side switch will have fully restored.

What is claimed is:

1. In a telephone exchange system, the combination with telephone lines, line relays for said lines, automatic finder switches, an extended starter Wire for associating an idle finder with said lines, release circuits therefor, a relay associated with each finder for rendering its release circuit inoperative,

vidle nder 'With said lines, olf-normal 'contacts associated lWith said .ft'iders, Arelease circuits for said finders, la relay-associated with each finder -for rendering its t'rel'ea'se circuit inoperative, `I neais actuated by the energization ot any line relay 'for operating the 4relays of the 'nders through Vwhich the starter vWire is extended, "of a relay for preventing the `operation 'of said means, A*and a circuit for said relay including the olf'- normal contacts "of all of 'sa-id nders in series. t y

3. In a telephone exchange system, "the combination with telephone lines, line renys for said unes, automatic Vfinder Switdhes, side switches therefor, 'an extended starter wire for associatingan idle finder With 'said lines, 4release "circuits v"for said "finders, a "relay associated With-each finder Tor rendering its leases release circuit inoperative, and means actuated by the lenergiZa'tion of any line 'relay for operating the relays of y'the 'finders through''vlrich the starter Wire is e'irztendcd, of a slow relay `for preventing the'op'eration of said means, and a circuit lfor said relay including side-'switch arms of all of said finders in series.`

4. I'n a telephone exchange system, cthe combination With telephone lines, line "relays therefor, yautomatic inder switches, an extended starter Wire lfor associating an idle finder With said lines, off-normal contacts therefor, vvrelease circuits for said finders, 'a relay '(5) :associated with each finder for rendering its release `circuit inoperative, a circuit for operating 4the relay of the finder :allotted to the lcalling line group closed upon the Aer'iergization 'of line relay of 'a line in suoli group, 'a circuit closed by said relay and including ythe relays (b) of the nders through which the starter Wire is extended, 'of a 'relay (180) orpreye'nting the closure Aof said circuit, and a circuit for saidrelay including `olf-normal lcontacts of all the finders 4in series. y

In witness whereof, I hereunto subscribe my name this r18th day of November, A. D.

BERT G. DUNHAM.

Copies of this patent may be obtained v"for vvcents each, by add're'sfsing` the Commissioner of Patents, Washington, lJJC. 

